Plate XX. 



Figure 1.— Left humerus of Pteranodon sp., No. 2709; inferior view, x 0.39 



Figure 2. — Left humerus of Pteranodon sp., No. 2831 ; superior view, x 0.39 



Figure 3. — Left humerus of Pteranodon sp., No. 2589 ; inferior view, x 0.39 



Figure 4. — Left humerus of Pteranodon sp., No. 2302 ; anterior view, x 0.39 

 Figure 5. — The same bone ; posterior view, x 0.39 

 Figure 6. — Right humerus of Pteranodon sp., No. 2730 ; superior view. > 0.39 



